U.S. consumer prices rose less than expected in September, held back by a slower increase in the cost of rent and falling energy prices, as underlying inflation pressures appeared to cool slightly.

The modest price increases come despite a U.S. labor market that looks robust by most measures. With the readings only slightly below what analysts expected, the inflation report is not likely to impact expectations the Federal Reserve will raise interest rates at its December policy meeting. U.S. Treasury yields extended their fall while U.S. stock index futures pared losses, as the data dented expectations of a more aggressive pace of Fed rate hikes. The dollar held at lower levels against a basket of currencies.

The Consumer Price Index increased 0.1 percent last month after rising 0.2 percent in August, the Labor Department said. In the 12 months through September, the CPI increased 2.3 percent, slowing from August's 2.7 percent advance.

Excluding the volatile food and energy components, the CPI edged up 0.1 percent for the second straight month. The so-called core index had increased 0.2 percent in May, June and July.

In the 12 months through September, the core CPI increased 2.2 percent.

Owners' equivalent rent of primary residence, which is what a homeowner would pay to rent or receive from renting a home, rose 0.2 percent in September after rising 0.3 percent in August. Rental prices for primary residences rose 0.2 percent, down from a 0.4 percent increase in August.

Separately, the Labor Department said initial claims for state unemployment benefits increased 7,000 to a seasonally adjusted 214,000 for the week ended Oct. 6. While analysts had expected a slight decline, the reading still remained near a 49-year low.

The four-week moving average of initial claims, considered a better measure of labor market trends as it irons out week-to-week volatility, rose 2,500 to 209,500 last week.